Interpretive Summary:
The lack of winter hardiness in winter oat makes it difficult to grow in many cold regions of the world. Winter hardiness is a very complex trait that can be divided into components that may be analyzed separately and recombined to form more winter hardy cultivars. Identifying genotypes with superior levels of each separate component is the objective of quantitative trait loci (QTL) analysis. In this study several QTL (pieces of DNA) were associated with the traits, field winter survival, crown freeze survival vernalization and photoperiod response. Being able to identify individual genotypes with superior levels of these traits without having to do field evaluations will give breeders a more efficient way to develop winter hardy cultivars.

Technical Abstract:
Winter hardiness is a complex trait and poor winter hardiness limits commercial production of winter oat. The objective of this study was to identify Quantitative Trait Loci (QTL) for the winter hardiness component traits: winter field survival, crown freeze tolerance, heading date, plant height and vernalization response in a recombinant inbred line population derived from a cross of winter tender ‘Fulghum’ by winter hardy ‘Norline’. Crown freeze tolerance, vernalization response, and photoperiod response were evaluated in controlled environment studies. Heading date and plant height were evaluated over two seasons in Kinston, North Carolina, and winter field survival was evaluated in five environments over two seasons in the mountains of North Carolina and Virginia. A genetic linkage map was developed using RFLP and SSR markers. Multiple interval mapping and EPISTACY were used to identify QTL. Most QTL were located on linkage groups FN3, FN22 and FN24 which corresponded to regions carrying winter hardiness QTL in other oat populations. QTL were identified for all traits except photoperiod response, and epistatic interactions were identified for winter field survival, crown freeze tolerance, vernalization response and plant height. Major QTL for winter field survival (R2=35%) and crown freeze tolerance (R2 =52%) were identified on linkage group FN3 which was associated with an intergenomic reciprocal translocation between chromosomes 7C and 17. These results have improved our understanding of the interaction of winter hardiness traits and identified a strategy for oat winter hardiness improvement.